There will be a 24-hour interval between each dosing. On Dosing Days 1 (first dosing) and 5 (last dosing) subjects will continue fasting for the next 4 hours post-dose, at which time a meal will be provided. Water will be allowed freely until one hour before, and from one hour after each dosing. Standardized meals will be provided according to the schedule Blood for PK analysis of metadoxine components (pyrrolidone-5-carboxylate L-pyroglutamic acid and pyridoxine) will be sampled serially following dosing as per the schedule in the PK Evaluation Subjects will be discharged from the CRC approximately 24 hours after the last dose.